Objective: Whole body I-131 scanning (WBS), as a standard method in the evaluation of patients with differentiated thyroid carcinoma (DTC), has some limitations in distinguishing between physiological and pathological tracer uptake and in defining exact anatomical localization of pathological foci. The purpose of our study was to determine the additional diagnostic value of the SPECT/CT in patients with DTC.
Methods: One hundred and forty-two patients with previous total thyroidectomy who underwent diagnostic or post-therapeutic WB imaging were included in this retrospective study. The distinction between physiological and pathological uptake could not be clearly done and/or the localization of pathological uptake could not be clearly defined on WBS, were considered as inconclusive finding and regional SPECT/CT images of these patients were evaluated.
Results: The number of pathological foci detected by WBS and SPECT/CT was 64 and 59 respectively. Exact anatomical localization was determined in 85.9% of the lesions with SPECT/CT. Benign accumulations (inflammatory / physiological) were determined in 12.5% of inconclusive foci. In 14.1% of WBS detected foci, no significant tracer uptake was observed on SPECT/CT images. Four additional foci were detected on SPECT/CT (3 thyroid remnant, 1 bone).
Conclusion: SPECT/CT improves the specificity of I-131 scanning and contributes to the management of DTC patients.